Commitments and Contingencies (Details)			3 Months Ended	12 Months Ended		32 Months Ended
	Mar. 22, 2018 USD ($)	Mar. 23, 2015	Mar. 31, 2019 USD ($) claim	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2019 USD ($) claim	Jun. 17, 2013 USD ($)
Long-term Purchase Commitment [Line Items]
Site contingency, recovery from third party of environmental remediation cost						$ 12,200,000
Number of remaining claim to be resolved | claim			2			2
Bankruptcy claims amount of claims to be settled			$ 22,400,000			$ 22,400,000
Estimated value of claims remaining to be settled			500,000			500,000
Maximum bankruptcy claims remaining			$ 22,400,000			$ 22,400,000
Predecessor working ownership percentage			3.40%			3.40%
Allowed claims, settlement ratio			0.0544
Wyoming Refinery One
Long-term Purchase Commitment [Line Items]
Environmental remediation accrual			$ 17,100,000			$ 17,100,000
Environmental costs recognized, period for recognition of one third costs			5 years
Environmental costs recognized, remainder, period for recognition			30 years
Wyoming Refinery Two | Waste Water Treatment System
Long-term Purchase Commitment [Line Items]
Environmental remediation accrual			$ 11,600,000			11,600,000
Wyoming Refinery
Long-term Purchase Commitment [Line Items]
Loss contingency, range of possible loss			100,000			100,000
United Steelworkers Union
Long-term Purchase Commitment [Line Items]
Collective bargaining arrangement, extension term		4 years
Tesoro Corporation
Long-term Purchase Commitment [Line Items]
Contingent consideration (up to)							$ 20,000,000
Loss contingency, damages paid	$ 10,500,000			$ 16,800,000
Loss contingency, damages sought				$ 8,300,000	$ 4,300,000
Tesoro Corporation | Maximum
Long-term Purchase Commitment [Line Items]
Contingent consideration (up to)							$ 40,000,000
Tesoro Corporation | Indemnification Agreement
Long-term Purchase Commitment [Line Items]
Deductible for indemnification obligation			1,000,000			1,000,000
Indemnification obligation cap			$ 15,000,000			$ 15,000,000